Effects of Diet versus Gastric Bypass on Metabolic Function in Diabetes

Gut microbiota alterations induced by Roux-en-Y gastric bypass result in glucose-lowering by enhancing intestinal glucose excretion

Roux-en-Y gastric bypass (RYGB) results in glucose-lowering in patients with type 2 diabetes mellitus (T2DM) and may be associated with increased intestinal glucose excretion. However, the contribution of intestinal glucose excretion to glycemic control after RYGB and its underlying mechanisms are not fully elucidated. Here, we confirmed that intestinal glucose excretion significantly increased in obese rats after RYGB, which was negatively correlated with postoperative blood glucose levels. Moreover, we also found that the contribution of Biliopancreatic limb length, an important factor affecting glycemic control after RYGB, to the improvement of glucose metabolism after RYGB attributed to the enhancement of intestinal glucose excretion. Subsequently, we further determined through multiple animal models that intestinal glucose excretion is physiological rather than pathological and plays a crucial role in maintaining glucose homeostasis in the body. Finally, we employed germ-free mice colonized with fecal samples from patients and rats to demonstrate that enhanced intestinal glucose excretion after RYGB is directly modulated by the surgery-induced changes in the gut microbiota. These results indicated that the gut microbiota plays a direct causal role in the hypoglycemic effect of RYGB by promoting intestinal glucose excretion, which may provide new insights for developing gut microbiota-based therapies for T2DM.

Bile acid metabolism in type 2 diabetes mellitus

Type 2 diabetes mellitus is a complex disorder associated with insulin resistance and hyperinsulinaemia that is insufficient to maintain normal glucose metabolism. Changes in insulin signalling and insulin levels are thought to directly explain many of the metabolic abnormalities that occur in diabetes mellitus, such as impaired glucose disposal. However, molecules that are directly affected by abnormal insulin signalling might subsequently go on to cause secondary metabolic effects that contribute to the pathology of type 2 diabetes mellitus. In the past several years, evidence has linked insulin resistance with the concentration, composition and distribution of bile acids. As bile acids are known to regulate glucose metabolism, lipid metabolism and energy balance, these findings suggest that bile acids are potential mediators of metabolic distress in type 2 diabetes mellitus. In this Review, we highlight advances in our understanding of the complex regulation of bile acids during insulin resistance, as well as how bile acids contribute to metabolic control.

Subcutaneous adipose tissue and skeletal muscle mitochondria following weight loss

Obesity is a major global health issue with various metabolic complications. Both bariatric surgery and dieting achieve weight loss and improve whole-body metabolism, but vary in their ability to maintain these improvements over time. Adipose tissue and skeletal muscle metabolism are crucial in weight regulation, and obesity is linked to mitochondrial dysfunction in both tissues. The impact of bariatric surgery versus dieting on adipose tissue and skeletal muscle mitochondrial metabolism remains to be elucidated. Understanding the molecular pathways that modulate tissue metabolism following weight loss holds potential for identifying novel therapeutic targets in obesity management. This narrative review summarizes current knowledge on mitochondrial metabolism following bariatric surgery and diet-induced weight loss in adipose tissue and skeletal muscle, and sheds light on their respective effects.

Cardioprotective benefits of metabolic surgery and GLP-1 receptor agonist-based therapies

Individuals with excessive adipose tissue and type 2 diabetes mellitus (T2DM) face a heightened risk of cardiovascular morbidity and mortality. Metabolic surgery is an effective therapy for people with severe obesity to achieve significant weight loss. Additionally, metabolic surgery improves blood glucose levels and can lead to T2DM remission, reducing major adverse cardiovascular outcomes (MACE). Glucagon-like peptide 1 (GLP-1) receptor agonists (GLP-1RAs) are a class of medication that effectively reduce body weight and MACE in patients with T2DM. This review explores the potential mechanisms underlying the cardioprotective benefits of metabolic surgery and GLP-1RA-based therapies and discusses recent evidence and emerging therapies in this dynamic area of research.

Changes in insulin sensitivity and gut peptides 8 and 52 weeks after bariatric surgery or low-calorie diet

The endocrine consequences of weight loss by bariatric surgery (BS) and caloric restriction are not fully understood but contribute to variable improvements in insulin sensitivity and cardiometabolic health. This study compared changes in insulin sensitivity and plasma concentrations of gut peptides 8 weeks and 1 year after BS and a low-calorie diet (LCD). Nineteen female patients with obesity self-selected BS (gastric bypass [n = 5] or sleeve gastrectomy [n = 7]) or LCD (n = 7) in this parallel-arm, prospective observational study. We assessed insulin sensitivity via a two-step hyperinsulinemic-euglycemic clamp (20 and 80 mU/min/m2 insulin). Plasma glucose, insulin, and gut peptides were measured around a mixed meal tolerance test (400 kcal). Visual analogue scales (VAS) were used to rate subjective appetite sensations. All assessments were conducted at baseline and after 8 weeks and 1 year of intervention. Whole-body insulin sensitivity was unchanged 8 weeks after the intervention. One year after surgery, insulin sensitivity at both 20 and 80 mU/m2/min insulin infusion doses increased with BS weight loss (-33.8% ± 1.4% body weight) but was unchanged in LCD with small weight loss (-3.7% ± 2.0% body weight). Postprandial total PYY increased more following BS while total and acylated ghrelin decreased more following BS compared to LCD. Hunger decreased and fullness increased with BS compared to LCD (p = .037; p = .010, respectively). Insulin sensitivity was improved only 1 year after BS, despite significant weight loss after 8 weeks. Changes in gut peptides after BS paralleled reduced hunger and increased fullness. Most improvements in cardiometabolic health were related to weight loss.

Altered postprandial glucose metabolism and enteropancreatic hormone responses during pregnancy following Roux-en-Y gastric bypass: a prospective cohort study

INTRODUCTION

Roux-en-Y gastric bypass (RYGB) increases the risk of postprandial hypoglycemia, whereas pregnancy decreases insulin sensitivity, which could be expected to counteract hypoglycemia. We examined if RYGB performed prior to pregnancy altered the postprandial glucose metabolism and enteropancreatic hormone responses to a mixed meal test (MMT).

RESEARCH DESIGN AND METHODS

Twenty-three women with RYGB and 23 women matched on prepregnancy body mass index and parity underwent a 4-hour MMT in the first and third trimester of pregnancy with measurement of circulating levels of glucose, insulin, C-peptide, glucose-dependent insulin peptide (GIP), glucagon-like peptide 1 (GLP-1), glucagon, free fatty acids, and lactate. Biochemical hypoglycemia was defined as plasma glucose <3.5 mmol/L.

RESULTS

Women with RYGB had earlier and higher peak glucose, lower nadir glucose levels, and a higher frequency of biochemical hypoglycemia compared with women without RYGB in both the first and third trimester. The lower glucose levels were preceded by markedly elevated total GLP-1 and insulin levels in women with RYGB, whereas total GIP levels were unaltered. The glucagon levels were lower in women with RYGB. In the first trimester MMT, peak and area under the curve of total plasma GLP-1 and serum insulin levels were negatively associated with nadir plasma glucose, while the early postmeal response of plasma glucagon was positively associated with nadir plasma glucose in the third trimester.

CONCLUSIONS

These results provide novel insights into the combined effects of RYGB and pregnancy on postmeal glucose metabolism and enteropancreatic hormone responses during pregnancy, and how these changes associate with an increased risk of postprandial hypoglycemia.

TRIAL REGISTRATION NUMBER

NCT03713060.

Myokines as potential mediators of changes in glucose homeostasis and muscle mass after bariatric surgery

Myokines are bioactive peptides released by skeletal muscle. Myokines exert auto-, para-, or endocrine effects, enabling them to regulate many aspects of metabolism in various tissues. However, the contribution of myokines to the dramatic changes in glucose homeostasis and muscle mass induced by bariatric surgery has not been established. Our review highlights that myokines such as brain-derived neurotrophic factor (BDNF), meteorin-like protein (Metrnl), secreted protein acidic and rich in cysteine (SPARC), apelin (APLN) and myostatin (MSTN) may mediate changes in glucose homeostasis and muscle mass after bariatric surgery. Our review also identifies myonectin as an interesting candidate for future studies, as this myokine may regulate lipid metabolism and muscle mass after bariatric surgery. These myokines may provide novel therapeutic targets and biomarkers for obesity, type 2 diabetes and sarcopenia.

Point-Counterpoint Debate: Surgery vs Medical Treatment for the Management of Obesity

Obesity is a chronic, relapsing condition with severe health risks and a huge economic burden. Effective interventions for severe obesity include bariatric or metabolic surgery and high-intensity medical management involving lifestyle changes and pharmacotherapy. This article summarizes the debate between Drs. Schauer and Rothberg at the June 2024 Endocrine Society meeting regarding the optimal approach to managing obesity, exploring mechanisms, outcomes, safety, quality-of-life, and cost-effectiveness. Metabolic surgery results in substantial and sustained weight loss, improvements in comorbidities such as type 2 diabetes, and reduced mortality, and it is cost-effective. However, it carries risks associated with surgery and long-term complications, and its high upfront costs limit its scalability. Conversely, high-intensity medical management, which includes comprehensive lifestyle interventions and pharmacotherapy, leads to meaningful, though sometimes less substantial, weight loss and health improvements. The latter approach prioritizes behavioral changes and is cost-effective but requires patient adherence and faces challenges with medication side effects and costs. Both interventions offer substantial health benefits; the choice between them should consider individual patient needs, health status, target weight loss, and personal preferences. Metabolic surgery may be more suitable for individuals with severe obesity or when comorbidities are inadequately controlled, whereas medical management may be more suited to patients with less severe obesity and those preferring nonsurgical options. Future research should investigate the combined effects of surgery and medical management and enhance access to and affordability of these treatments. A multidisciplinary, personalized approach will likely yield the best outcomes in managing this complex health issue.

Metabolic interventions as adjunctive therapies to insulin in type 1 diabetes: Current clinical landscape and perspectives

Type 1 diabetes (T1D) is classically characterized as an autoimmune disease wherein the immune system erroneously attacks insulin-producing pancreatic β-cells, causing insulin insufficiency and severe metabolic dysregulation. However, intensive investigation and numerous clinical trials with immunotherapies have been largely unable to significantly alter the course of disease. Currently, there is no effective way to prevent or cure T1D, and insulin remains the cornerstone of T1D treatment. In recent years, a growing body of research suggests that β-cells actively contribute to the immune response and to disease development. Factors including glucotoxicity, lipotoxicity, inflammation, endoplasmic reticulum (ER) and oxidative stress can induce β-cell apoptosis and senescence, further promoting insulitis. Recent studies highlight the importance of targeting metabolic control for T1D management and treatment. Metabolic interventions, through their direct and indirect impacts on β-cells, have shown promise in preserving β-cell function. These interventions can reduce glucose toxicity, alleviate oxidative stress and inflammation, enhance insulin sensitivity, and indirectly mitigate the autoimmune responses. By preserving β-cell function, individuals with T1D attain better glycaemic control, reduced complication risks and exhibit improved overall metabolic health. Here, we provide an overview of insights from clinical studies, systematic reviews and meta-analyses that collectively demonstrate that adjunctive metabolic interventions can enhance glycaemic control, reduce insulin requirements and mitigate adverse effects associated with insulin monotherapy. They also show potential for halting disease progression, preserving residual β-cell function and improving long-term outcomes for newly diagnosed individuals. Future research should focus on optimizing these treatment strategies and establishing their long-term efficacy and safety.

The Twin Cycle Hypothesis of type 2 diabetes aetiology: From concept to national NHS programme

The development of magnetic resonance methods for quantifying intra-organ metabolites has permitted advances in the understanding of fasting and post-prandial carbohydrate and lipid handling in people with and without type 2 diabetes. Insulin resistance in the liver was shown to be related to excess intra-organ fat and was able to be returned to normal by weight loss. The practical effect of having muscle insulin sensitivity in the lower part of the wide normal range resulted in the obligatory shunting of carbohydrates via de novo lipogenesis into saturated fat. These observations provided the basis for the Twin Cycle Hypothesis of the aetiology of type 2 diabetes. Subsequent studies on people with type 2 diabetes confirmed the postulated pathophysiological abnormalities and demonstrated their reversibility by dietary weight loss of 10-15 kg. Overall, the fundamental understanding of the mechanisms causing type 2 diabetes has bridged physiological and clinical perspectives. Large population-based randomised controlled trials confirmed the practical clinical application of the method of achieving substantial weight loss, and an NHS programme is now in place offering potential remission to people within 6 years of diagnosis.

Nutritional Strategies for Battling Obesity-Linked Liver Disease: the Role of Medical Nutritional Therapy in Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD) Management

PURPOSE OF REVIEW

This narrative review explores the role of Medical Nutritional Therapy (MNT) in managing Metabolic-Associated Steatotic Liver Disease (MASLD), previously known as nonalcoholic fatty liver disease. It aims to examine the effectiveness of specific nutritional strategies in preventing and treating this obesity-linked liver disease.

RECENT FINDINGS

Emerging evidence underscores the benefits of the Mediterranean diet, low-carbohydrate diets, and intermittent fasting in reducing liver fat, improving insulin sensitivity, and mitigating inflammation. Supplementing with vitamin E, omega-3 fatty acids, and silymarin can potentially reduce liver fibrosis and promote liver health. MNT is a key intervention for MASLD management, emphasizing dietary patterns, caloric restriction, and nutraceutical supplementation. Integrating these strategies with lifestyle modifications, including regular physical activity, offers a comprehensive approach to improving metabolic and liver outcomes in patients with MASLD. Further research is needed to refine and personalize these therapeutic interventions.

Roux-en-Y gastric bypass improves liver and glucose homeostasis in Zucker diabetic fatty rats by upregulating hepatic trefoil factor family 3 and activating the phosphatidylinositol 3-kinase/protein kinase B pathway

BACKGROUND

Roux-en-Y gastric bypass (RYGB) surgery is effective in ameliorating type 2 diabetes mellitus (T2DM); but its mechanism remains incompletely understood.

OBJECTIVES

This study aimed to investigate whether RYGB improves glucose metabolism by upregulating hepatic trefoil factor family 3 (TFF3) and thereby activating the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) pathway.

SETTING

Affiliated Hospital of North Sichuan Medical college in Nanchong city, China.

METHODS

Zucker diabetic fatty (ZDF) rats underwent RYGB or sham surgery (SHAM), and Zucker lean (ZL) rats served as controls (CON). TFF3 expression and PI3K/Akt pathway activity were compared between groups using western blot, immunofluorescence, and RT-qPCR. Adeno-associated virus (AAV) was used to specifically overexpress and interfere with hepatic TFF3. Liver fibrosis and steatosis were assessed using Masson trichrome and Oil Red O staining. HepG2 cells overexpressing or knocking out TFF3 were constructed using lentiviral transfection and CRISPR/Cas9 technology. After verifying the activity of the PI3K/Akt pathway by western blot, rescue experiments were performed on HepG2 cell overexpressing and knocking out TFF3 using LY294002 and 740Y-P, respectively. The activities of gluconeogenic enzymes and glucose uptake capacity in different HepG2 cells were evaluated using qPCR and flow cytometry.

RESULTS

Compared with the SHAM group, the blood glucose, body weight, insulin resistance, and lipid metabolism of ZDF rats in the RYGB group were significantly improved. The expression of TFF3 and PI3K/Akt phosphorylation in the liver of the RYGB group were higher than those of the rats that had undergone SHAM. In addition, compared with the SHAM group, the liver fibrosis and fatty degeneration of RYGB rats were milder, and the activity of gluconeogenic enzymes was lower. After tail vein injection of AAV that specifically overexpresses liver TTF3 in rats in the SHAM group, rats' insulin resistance, glucose tolerance, gluconeogenic enzymes, and other glucose metabolism indicators improved. After tail vein injection of AAV that interferes with liver TFF3 in rats in the RYGB group, rats' glucose metabolism indicators deteriorated. In in vitro experiments, the PI3K/Akt activity of TFF3-knocked-out HepG2 cells was lower than that of other groups. Lower glucose concentration were observed in TFF3-overexpressing cell lines. After rescue experiments, differences were found. The glucose metabolism level of the TFF3-expressing HepG2 cell line was positively correlated with the activity of the PI3K/Akt pathway.

CONCLUSIONS

RYGB regulates the expression of TFF3 in the liver of ZDF rats, thereby activating the PI3K/Akt pathway and improving T2DM.

The dual impact: physiological and psychological effects of rapid weight loss in wrestling

Introduction

Athletes competing in weight-class sports often seek to gain an advantage by competing at lower weights. Athletes competing in weight-class sports often seek to gain an advantage by competing at lower weights. To achieve this, they aim to lose weight during the competition period, leading to various physiological and psychological changes. This study aimed to investigate the biochemical, hormonal, and psychological effects of weight reduction in elite wrestlers during the competition phase.

Methods

Thirty-seven elite male free style wrestlers (age: 19.02 ± 1.27) participated in the study. Samples were collected 5 days before and on the day of the match.

Results

A significant decrease in body weight was observed (p < 0.05). Levels of creatine, BUN, sodium, hematocrit, hemoglobin, LDH, and cortisol increased, while albumin, testosterone, and FSH levels decreased. There were no significant differences in potassium, ALT, AST, TSH levels. State and trait anxiety scores of the wrestlers increased significantly during the RWL period.

Conclusion

The study concluded that elite wrestlers experienced significant changes in physiological and psychological parameters during the competition periods. These findings underscore the importance of careful monitoring of RWL strategies by coaches and athletes to mitigate the adverse effects on nutritional status, psychological well-being, and physical performance.

Effect of Weight Loss on Skeletal Muscle Bioactive Lipids in People With Obesity and Type 2 Diabetes

Muscle sn-1,2-diacylglycerol (DAG) and C18:0 ceramide accumulation in sarcolemmal and mitochondrial compartments have been proposed to regulate muscle insulin sensitivity. Here, we evaluated whether weight loss-induced improvements in insulin sensitivity were associated with changes in muscle sn-1,2-DAG and ceramide content in people with obesity and type 2 diabetes. We measured skeletal muscle insulin sensitivity, assessed by using the hyperinsulinemic-euglycemic clamp procedure in conjunction with stable isotopically labeled glucose tracer infusion, and skeletal muscle sn-1,2-DAG and ceramide contents by using liquid chromatography-tandem mass spectrometry after subcellular fractionation and DAG isomer separation in 14 adults with obesity and type 2 diabetes before and after marked (18.6 ± 2.1%) weight loss. Whole-body insulin sensitivity doubled after weight loss. Sarcolemmal sn-1,2-DAG and C18:0 ceramide contents after weight loss were not different from values before weight loss. In contrast, mitochondrial-endoplasmic reticulum (ER) C18:0 ceramide content decreased by ∼20% after weight loss (from 2.16 ± 0.08 to 1.71 ± 0.13 nmol/g, P < 0.005). These results suggest a decrease in muscle mitochondrial-ER C18:0 ceramide content could contribute to the beneficial effect of weight loss on skeletal muscle insulin sensitivity.

ARTICLE HIGHLIGHTS

Histological improvements following energy restriction and exercise: The role of insulin resistance in resolution of MASH

BACKGROUND & AIMS

Metabolic dysfunction-associated steatohepatitis (MASH) is one of the most common liver diseases worldwide and is characterized by multi-tissue insulin resistance. The effects of a 10-month energy restriction and exercise intervention on liver histology, anthropometrics, plasma biochemistries, and insulin sensitivity were compared to standard of care (control) to understand mechanisms that support liver health improvements.

METHODS

Following medical diagnosis of MASH, individuals were randomized to treatment (n = 16) or control (n = 8). Liver fat (magnetic resonance spectroscopy), 18-hour plasma biochemical measurements, and isotopically labeled hyperinsulinemic-euglycemic clamps were completed pre- and post-intervention. Body composition and cardiorespiratory fitness (VO2peak) were also measured mid-intervention. Those in the treatment group were counseled to reduce energy intake and completed supervised, high-intensity interval training (3x/week) for 10 months. Controls continued physician-directed care.

RESULTS

Treatment induced significant (p <0.05) reductions in body weight, fat mass, and liver injury, while VO2peak (p <0.05) and non-esterified fatty acid suppression (p = 0.06) were improved. Both groups exhibited reductions in total energy intake, hemoglobin A1c, hepatic insulin resistance, and liver fat (p <0.05). Compared to control, treatment induced a two-fold increase in peripheral insulin sensitivity which was significantly related to higher VO2peak and resolution of liver disease.

CONCLUSIONS

Exercise and energy restriction elicited significant and clinically meaningful treatment effects on liver health, potentially driven by a redistribution of excess nutrients to skeletal muscle, thereby reducing hepatic nutrient toxicity. Clinical guidelines should emphasize the addition of aerobic exercise in lifestyle treatments for the greatest histologic benefit in individuals with advanced MASH.

IMPACT AND IMPLICATIONS

The mechanisms that underpin histologic improvement in individuals with metabolic dysfunction-associated steatohepatitis (MASH) are not well understood. This study evaluated the relationship between liver and metabolic health, testing how changes in one may affect the other. We investigated the effects of energy restriction and exercise on the association between multi-tissue insulin sensitivity and histologic improvements in participants with biopsy-proven MASH. For the first time, these results show that an improvement in peripheral (but not hepatic) insulin sensitivity and systemic markers of muscle function (i.e. cardiorespiratory fitness) were strongly related to resolution of liver disease. Extrahepatic disposal of substrates and improved fitness levels supported histologic improvement, confirming the addition of exercise as crucial to lifestyle interventions in MASH.

CLINICAL TRIAL NUMBER

NCT03151798.

Metabolomic Fingerprints of Medical Therapy Versus Bariatric Surgery in Patients With Obesity and Type 2 Diabetes: The STAMPEDE Trial

OBJECTIVE

Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG) are effective procedures to treat and manage type 2 diabetes (T2D). However, the underlying metabolic adaptations that mediate improvements in glucose homeostasis remain largely elusive. The purpose of this study was to identify metabolic signatures associated with biochemical resolution of T2D after medical therapy (MT) or bariatric surgery.

RESEARCH DESIGN AND METHODS

Plasma samples from 90 patients (age 49.9 ± 7.6 years; 57.7% female) randomly assigned to MT (n = 30), RYGB (n = 30), or SG (n = 30) were retrospectively subjected to untargeted metabolomic analysis using ultra performance liquid chromatography with tandem mass spectrometry at baseline and 24 months of treatment. Phenotypic importance was determined by supervised machine learning. Associations between change in glucose homeostasis and circulating metabolites were assessed using a linear mixed effects model.

RESULTS

The circulating metabolome was dramatically remodeled after SG and RYGB, with largely overlapping signatures after MT. Compared with MT, SG and RYGB profoundly enhanced the concentration of metabolites associated with lipid and amino acid signaling, while limiting xenobiotic metabolites, a function of decreased medication use. Random forest analysis revealed 2-hydroxydecanoate as having selective importance to RYGB and as the most distinguishing feature between MT, SG, and RYGB. To this end, change in 2-hydroxydecanoate correlated with reductions in fasting glucose after RYGB but not SG or MT.

CONCLUSIONS

We identified a novel metabolomic fingerprint characterizing the longer-term adaptations to MT, RYGB, and SG. Notably, the metabolomic profiles of RYGB and SG procedures were distinct, indicating equivalent weight loss may be achieved by divergent effects on metabolism.

Effects of weight loss from oral semaglutide administration on cardiometabolic risk factors in Japanese patients with type 2 diabetes: a retrospective analysis using propensity score matching

Background

Obesity is increasingly being recognized as a chronic disease that exacerbates type 2 diabetes and its related complications. Oral semaglutide, a novel glucagon-like peptide-1 (GLP-1) receptor agonist, has demonstrated efficacy in weight loss and diabetes control in Western populations. However, in real-world clinical practice, its effectiveness in Japanese patients, who typically exhibit a leaner phenotype and unique genetic susceptibilities affecting insulin secretion, remains unclear.

Methods

We retrospectively evaluated the electronic medical records of 313 patients treated with oral semaglutide and 11,239 untreated controls at the Keio University School of Medicine. We performed propensity score matching to adjust for covariates, including age, sex, height, weight, blood pressure, blood test data, medications, and compared the cardiometabolic risk factors, including HbA1c, blood pressure, lipids, and liver function 180 days post-treatment, of both patient groups. We conducted a subgroup analysis for patients who achieved ≥ 3% weight loss.

Results

After propensity score matching, the semaglutide group demonstrated significantly better outcomes for HbA1c reduction and weight loss and improvements in systolic blood pressure (SBP), low-density lipoprotein cholesterol (LDL-C), and liver function than the control group. Subgroup analysis of patients with ≥ 3% weight loss revealed superior HbA1c improvements in the semaglutide group; however, no significant differences in other metabolic parameters, such as SBP, LDL-C, and liver function, were observed.

Conclusion

Oral semaglutide effectively improved metabolic markers in Japanese patients with type 2 diabetes, similar to that in Western populations. Weight loss itself was suggested to significantly contribute to blood pressure, lipid levels, and liver function changes.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13340-024-00744-3.

Using Pre-operative Insulin Dose to Predict Diabetes Remission After Roux-En-Y Gastric Bypass and Sleeve Gastrectomy

BACKGROUND

Obesity is intricately associated with type-2 diabetes (T2D) and other cardiovascular conditions, increasing morbidity, mortality, and health care costs. Metabolic and bariatric surgeries (MBS) have shown promising results in significant weight loss and T2D remission, but existing predictive scores for post-MBS diabetes remission do not consider insulin dosage, potentially overlooking a critical factor.

METHODS

A retrospective analysis of patients with T2D who underwent Roux-en-Y gastric bypass (RYGB) or sleeve gastrectomy (SG). The study focused on insulin dosage impact, divided into quartiles, on remission rates post-MBS. The effectiveness of RYGB vs SG was compared within insulin dose quartiles with up to 5 years of follow up.

RESULTS

A total of 508 patients (64% female, 94.9% White, mean age 53.5 ± 10.5 years, BMI (46.0 ± 8.3 kg/m2) were included in the analysis. This study demonstrates a profound association between insulin dosage quartiles and T2D remission after MBS. Patients with lower insulin requirements showed superior remission rates; those in the lowest quartile had remission rates of 73%, 70%, and 62% at 1, 3, and 5 years, respectively, compared to 34%, 37%, and 36% in the highest quartile (P < 0.001 across all intervals). RYGB surgery showed a significantly better remission in the second and third insulin quartiles, suggesting its effectiveness over SG for patients with mid-range insulin requirements.

CONCLUSION

This study underscores the importance of considering insulin dosage when predicting T2D remission post-MBS. The findings advocate for a more nuanced selection of MBS procedures based on individual insulin profiles, potentially enhancing diabetes remission outcomes.

Gastric Bypass vs Diet and Cardiovascular Risk Factors: A Nonrandomized Controlled Trial

Importance

Roux-en-Y gastric bypass (RYGB) is associated with reduced cardiovascular (CV) risk factors, morbidity, and mortality. Whether these effects are specifically induced by the surgical procedure or the weight loss is unclear.

Objective

To compare 6-week changes in CV risk factors in patients with obesity undergoing matching caloric restriction and weight loss by RYGB or a very low-energy diet (VLED).

Design, Setting, and Participants

This nonrandomized controlled study (Impact of Body Weight, Low Calorie Diet, and Gastric Bypass on Drug Bioavailability, Cardiovascular Risk Factors, and Metabolic Biomarkers [COCKTAIL]) was conducted at a tertiary care obesity center in Norway. Participants were individuals with severe obesity preparing for RYGB or a VLED. Recruitment began February 26, 2015; the first patient visit was on March 18, 2015, and the last patient visit (9-week follow-up) was on August 9, 2017. Data were analyzed from April 30, 2021, through June 29, 2023.

Interventions

VLED alone for 6 weeks or VLED for 6 weeks after RYGB; both interventions were preceded by 3-week LED.

Main Outcomes and Measures

Between-group comparisons of 6-week changes in CV risk factors.

Results

Among 78 patients included in the analyses, the mean (SD) age was 47.5 (9.7) years; 51 (65%) were women, and 27 (35%) were men. Except for a slightly higher mean (SD) body mass index of 44.5 (6.2) in the RYGB group (n = 41) vs 41.9 (5.4) in the VLED group (n = 37), baseline demographic and clinical characteristics were similar between groups. Major atherogenic blood lipids (low-density lipoprotein cholesterol, non-high-density lipoprotein cholesterol, apolipoprotein B, lipoprotein[a]) were reduced after RYGB in comparison with VLED despite a similar fat mass loss. Mean between-group differences were -17.7 mg/dL (95% CI, -27.9 to -7.5), -17.4 mg/dL (95% CI, -29.8 to -5.0) mg/dL, -9.94 mg/dL (95% CI, -15.75 to -4.14), and geometric mean ratio was 0.55 U/L (95% CI, 0.42 to 0.72), respectively. Changes in glycemic control and blood pressure were similar between groups.

Conclusions and Relevance

This study found that clinically meaningful reductions in major atherogenic blood lipids were demonstrated after RYGB, indicating that RYGB may reduce CV risk independent of weight loss.

Trial Registration

ClinicalTrials.gov Identifier: NCT02386917.

Understanding the cause of type 2 diabetes

Type 2 diabetes has long been thought to have heterogenous causes, even though epidemiological studies uniformly show a tight relationship with overnutrition. The twin cycle hypothesis postulated that interaction of self-reinforcing cycles of fat accumulation inside the liver and pancreas, driven by modest but chronic positive calorie balance, could explain the development of type 2 diabetes. This hypothesis predicted that substantial weight loss would bring about a return to the non-diabetic state, permitting observation of the pathophysiology determining the transition. These changes were postulated to reflect the basic mechanisms of causation in reverse. A series of studies over the past 15 years has elucidated these underlying mechanisms. Together with other research, the interaction of environmental and genetic factors has been clarified. This knowledge has led to successful implementation of a national programme for remission of type 2 diabetes. This Review discusses the paucity of evidence for heterogeneity in causes of type 2 diabetes and summarises the in vivo pathophysiological changes, which cause this disease of overnutrition. Type 2 diabetes has a homogenous cause expressed in genetically heterogenous individuals.

A multifaceted and inclusive methodology for the detection of sarcopenia in patients undergoing bariatric surgery: an in-depth analysis of current evidence

Bariatric surgery is widely recognized as the most effective intervention for obesity and offers benefits beyond weight loss. However, not all patients achieve satisfactory weight loss, balanced changes in body composition, and resolution of comorbidities. Therefore, thorough pre- and postoperative evaluations are important to predict success and minimize adverse effects. More comprehensive assessments require broadening the focus beyond body weight and fat measurements to consider quantitative and qualitative evaluations of muscles. Introducing the concept of sarcopenia is useful for assessing the degradative and pathological changes in muscles associated with cardiometabolic function, physical performance, and other obesity-related comorbidities in patients undergoing bariatric surgery. However, there is currently no consensus or definition regarding the research and clinical use of sarcopenia in patients undergoing bariatric surgery. Therefore, this review aimed to define the concept of sarcopenia applicable to patients undergoing bariatric surgery, based on the consensus reached for sarcopenia in the general population. We also discuss the methods and significance of measuring muscle mass, quality, and strength, which are key variables requiring a comprehensive assessment.

Obesity and MASLD: Is weight loss the (only) key to treat metabolic liver disease?

Metabolic dysfunction-associated steatotic liver disease (MASLD) closely associates with obesity and type 2 diabetes. Lifestyle intervention and bariatric surgery aiming at substantial weight loss are cornerstones of MASLD treatment by improving histological outcomes and reducing risks of comorbidities. Originally developed as antihyperglycemic drugs, incretin (co-)agonists and SGLT2 inhibitors also reduce steatosis and cardiorenovascular events. Certain incretin agonists effectively improve histological features of MASLD, but not fibrosis. Of note, beneficial effects on MASLD may not necessarily require weight loss. Despite moderate weight gain, one PPARγ agonist improved adipose tissue and MASLD with certain benefit on fibrosis in post-hoc analyses. Likewise, the first THRβ-agonist was recently provisionally approved because of significant improvements of MASLD and fibrosis. We here discuss liver-related and metabolic effects induced by different MASLD treatments and their association with weight loss. Therefore, we compare results from clinical trials on drugs acting via weight loss (incretin (co)agonists, SGLT2 inhibitors) with those exerting no weight loss (pioglitazone; resmetirom). Furthermore, other drugs in development directly targeting hepatic lipid metabolism (lipogenesis inhibitors, FGF21 analogs) are addressed. Although THRβ-agonism may effectively improve hepatic outcomes, MASLD treatment concepts should consider all cardiometabolic risk factors for effective reduction of morbidity and mortality in the affected people.

Alterations in bile acid kinetics after bariatric surgery in patients with obesity with or without type 2 diabetes

BACKGROUND

Bariatric surgery is an effective treatment option for obesity and provides long-term weight loss and positive effects on metabolism, but the underlying mechanisms are poorly understood. Alterations in bile acid metabolism have been suggested as a potential contributing factor, but comprehensive studies in humans are lacking.

METHODS

In this study, we analysed the postprandial responses of bile acids, C4 and FGF19 in plasma, and excretion of bile acids in faeces, before and after bariatric surgery in patients (n = 38; 74% females) with obesity with or without type 2 diabetes from the BARIA cohort.

FINDINGS

We observed that total fasting plasma bile acid levels increased, and faecal excretion of bile acids decreased after surgery suggesting increased reabsorption of bile acids. Consistent with increased bile acid levels after surgery we observed increased postprandial levels of FGF19 and suppression of the bile acid synthesis marker C4, suggesting increased FXR activation in the gut. We also noted that a subset of bile acids had altered postprandial responses before and after surgery. Finally, fasting plasma levels of 6α-hydroxylated bile acids, which are TGR5 agonists and associated with improved glucose metabolism, were increased after surgery and one of them, HDCA, covaried with diabetes remission in an independent cohort.

INTERPRETATION

Our findings provide new insights regarding bile acid kinetics and suggest that bariatric surgery in humans alters bile acid profiles leading to activation of FXR and TGR5, which may contribute to weight loss, improvements in glucose metabolism, and diabetes remission.

FUNDING

Novo Nordisk Fonden, Leducq Foundation, Swedish Heart-Lung Foundation, Knut and Alice Wallenberg Foundation, the ALF-agreement, ZonMw.

Hepatic glucagon action: beyond glucose mobilization

Glucagon's ability to promote hepatic glucose production has been known for over a century, with initial observations touting this hormone as a diabetogenic agent. However, glucagon receptor agonism [when balanced with an incretin, including glucagon-like peptide 1 (GLP-1) to dampen glucose excursions] is now being developed as a promising therapeutic target in the treatment of metabolic diseases, like metabolic dysfunction-associated steatotic disease/metabolic dysfunction-associated steatohepatitis (MASLD/MASH), and may also have benefit for obesity and chronic kidney disease. Conventionally regarded as the opposing tag-team partner of the anabolic mediator insulin, glucagon is gradually emerging as more than just a "catabolic hormone." Glucagon action on glucose homeostasis within the liver has been well characterized. However, growing evidence, in part thanks to new and sensitive "omics" technologies, has implicated glucagon as more than just a "glucose liberator." Elucidation of glucagon's capacity to increase fatty acid oxidation while attenuating endogenous lipid synthesis speaks to the dichotomous nature of the hormone. Furthermore, glucagon action is not limited to just glucose homeostasis and lipid metabolism, as traditionally reported. Glucagon plays key regulatory roles in hepatic amino acid and ketone body metabolism, as well as mitochondrial turnover and function, indicating broader glucagon signaling consequences for metabolic homeostasis mediated by the liver. Here we examine the broadening role of glucagon signaling within the hepatocyte and question the current dogma, to appreciate glucagon as more than just that "catabolic hormone."

Obesity management for the treatment of type 2 diabetes: emerging evidence and therapeutic approaches

Excess adiposity can contribute to metabolic complications, such as type 2 diabetes mellitus (T2DM), which poses a significant global health burden. Traditionally viewed as a chronic and irreversible condition, T2DM management has evolved and new approaches emphasizing reversal and remission are emerging. Bariatric surgery demonstrates significant improvements in body weight and glucose homeostasis. However, its complexity limits widespread implementation as a population-wide intervention. The identification of glucagon-like peptide 1 (GLP-1) and the development of GLP-1 receptor agonists (GLP-1RAs) have improved T2DM management and offer promising outcomes in terms of weight loss. Innovative treatment approaches combining GLP-1RA with other gut and pancreatic-derived hormone receptor agonists, such as glucose-dependant insulinotropic peptide (GIP) and glucagon (GCG) receptor agonists, or coadministered with amylin analogues, are demonstrating enhanced efficacy in both weight loss and glycemic control. This review aims to explore the benefits of bariatric surgery and emerging pharmacological therapies such as GLP-1RAs, and dual and triple agonists in managing obesity and T2DM while highlighting the caveats and evolving landscape of treatment options.

Continued Diabetes Remission Despite Weight Recurrence: Gastric Bypass Long-Term Metabolic Benefit

BACKGROUND

Roux-en-Y gastric bypass (RYGB) demonstrates high rates of type 2 diabetes mellitus (T2DM) remission, a phenomenon hypothesized to be mediated mainly by weight loss. Compared with procedures that do not bypass the proximal small intestines, such as sleeve gastrectomy (SG), RYGB exhibits weight loss-independent intestinal mechanisms conducive to T2DM remission. We investigated continued diabetes remission (CDR) rates despite weight recurrence (WR) after RYGB compared with an SG cohort.

STUDY DESIGN

A retrospective review of patients who underwent successful primary RYGB or SG with a BMI value of 35 kg/m 2 or more and a preoperative diagnosis of T2DM was performed. Patients with less than 5 years of follow-up, absence of WR, or lack of T2DM remission at nadir weight were excluded. After selecting the optimal procedure for glycemic control, rates of CDR were then stratified into WR quartiles and compared.

RESULTS

A total of 224 RYGB and 46 SG patients were analyzed. The overall rate of CDR was significantly higher in the RYGB group (75%) compared with the SG group (34.8%; p < 0.001). The odds of T2DM recurrence were 5.5 times higher after SG compared with RYGB. Rates of CDR were stratified into WR quartiles (85.5%, <25%; 81.7%, 25% to 44.9%; 63.2%, 45% to 74.9%; and 60%, >75%). Baseline insulin use, higher preoperative glycosylated hemoglobin, and longer preoperative duration of T2DM were associated with T2DM recurrence, whereas WR was not.

CONCLUSIONS

T2DM remission rates after RYGB are maintained despite WR, arguing for a concurrent weight loss-independent metabolic benefit likely facilitated by bypassing the proximal small intestine.

CMKLR1 senses chemerin/resolvin E1 to control adipose thermogenesis and modulate metabolic homeostasis

Induction of beige fat for thermogenesis is a potential therapy to improve homeostasis against obesity. β3-adrenoceptor (β3-AR), a type of G protein-coupled receptor (GPCR), is believed to mediate the thermogenesis of brown fat in mice. However, β3-AR has low expression in human adipose tissue, precluding its activation as a standalone clinical modality. This study aimed at identifying a potential GPCR target to induce beige fat. We found that chemerin chemokine-like receptor 1 (CMKLR1), one of the novel GPCRs, mediated the development of beige fat via its two ligands, chemerin and resolvin E1 (RvE1). The RvE1 levels were decreased in the obese mice, and RvE1 treatment led to a substantial improvement in obese features and augmented beige fat markers. Inversely, despite sharing the same receptor as RvE1, the chemerin levels were increased in obesogenic conditions, and chemerin treatment led to an augmented obese phenotype and a decline of beige fat markers. Moreover, RvE1 and chemerin induced or restrained the development of beige fat, respectively, via the mechanistic target of rapamycin complex 1 (mTORC1) signaling pathway. We further showed that RvE1 and chemerin regulated mTORC1 signaling differentially by forming hydrogen bonds with different binding sites of CMKLR1. In conclusion, our study showed that RvE1 and chemerin affected metabolic homeostasis differentially, suggesting that selectively modulating CMKLR1 may be a potential therapeutic target for restoring metabolic homeostasis.

Contemporary Clinical Perspectives on Targeting Remission of Type 2 Diabetes

It has long been known that some patients with type 2 diabetes (T2DM) can experience sustained metabolic improvement to near-normal levels of glycemia either spontaneously or after medical intervention. Now recognized as remission of diabetes, this intriguing state is currently more feasible than ever before due to profound advances in metabolic surgery, pharmacologic therapy, and regimens of lifestyle modification. This enhanced capacity to induce remission has revealed new pathophysiologic insights, including the presence of a reversible component of the pancreatic beta-cell dysfunction that otherwise drives the chronic progressive nature of T2DM. In doing so, it has changed the therapeutic landscape by offering new potential management objectives and considerations for patients and providers. However, the excitement around these developments must also be tempered by the sobering realities of our current understanding of remission, including the recognition that this condition may not be permanent (resulting in glycemic relapse over time) and that beta-cell function may not be normalized in the setting of remission. These limitations highlight both the many gaps in our current understanding of remission and the caution with which clinical discussions must be handled for clear patient-directed communication of the pros and cons of targeting this outcome in practice. In this mini-review, we consider this rapidly growing literature, including its implications and its limitations, and thereby seek to provide objective balanced perspectives on targeting remission of T2DM in current clinical care.

Comparative impact of Roux-en-Y gastric bypass, sleeve gastrectomy or diet alone on beta-cell function in insulin-treated type 2 diabetes patients

Although bariatric surgery is an effective treatment for type 2 diabetes by inducing weight loss and augmenting gut hormone secretion, the immediate effect on beta-cell function itself remains to be elucidated in type 2 diabetes. Therefore, a prospective, randomized trial was performed in 30 patients with insulin-treated type 2 diabetes and a body mass index ≥ 35 kg/m2. Patients were randomly assigned (1:1:1) to Roux-en-Y gastric bypass (RYGB) or sleeve gastrectomy (SG) in combination with protein-sparing modified fast (PSMF), or to PSMF alone. Eu- and hyperglycemic clamps were performed before and 3 weeks after surgery and/or PSMF initiation. The primary outcome was the evolution of insulin sensitivity and beta-cell function after surgery, calculated using the composite measures of glucose disposal rate, insulin secretion rate, and disposition index (DI). Results revealed that markers of insulin sensitivity increased similarly in all arms (p = 0.43). A higher marker for maximal beta-cell function was observed when comparing SG to PSMF (p = 0.007). The DI showed a clear positive evolution after RYGB and SG, but not after PSMF alone. Altogether, these findings indicate that bariatric surgery results in an immediate beta-cell function recovery in insulin-treated type 2 diabetes.

The Effect of Diet Composition on the Post-operative Outcomes of Roux-en-Y Gastric Bypass in Mice

PURPOSE

Roux-en-Y gastric bypass (RYGB) leads to the improvement of many obesity-associated conditions. The degree to which post-operative macronutrient composition contributes to metabolic improvement after RYGB is understudied.

METHODS

A mouse model of RYGB was used to examine the effects of diet on the post-operative outcomes of RYGB. Obese mice underwent either Sham or RYGB surgery and were administered either chow or HFD and then monitored for an additional 8 weeks.

RESULTS

After RYGB, reductions to body weight, fat mass, and lean mass were similar regardless of diet. RYGB and HFD were independently detrimental to bone mineral density and plasma vitamin D levels. Independent of surgery, HFD accelerated hematopoietic stem and progenitor cell proliferation and differentiation and exhibited greater myeloid lineage commitment. Independent of diet, systemic iron deficiency was present after RYGB. In both Sham and RYGB groups, HFD increased energy expenditure. RYGB increased fecal energy loss, and HFD after RYGB increased fecal lipid content. RYGB lowered fasting glucose and liver glycogen levels but HFD had an opposing effect. Indices of insulin sensitivity improved independent of diet. HFD impaired improvements to dyslipidemia, NAFLD, and fibrosis.

CONCLUSION

Post-operative diet plays a significant role in determining the degree to which RYGB reverses obesity-induced metabolic abnormalities such as hyperglycemia, dyslipidemia, and NAFLD. Diet composition may be targeted in order to assist in the treatment of post-RYGB bone mineral density loss and vitamin D deficiency as well as to reverse myeloid lineage commitment. HFD after RYGB continues to pose a significant multidimensional health risk.

Critical Evaluation of Indices Used to Assess β-Cell Function

The assessment of β-cell function, defined as the relationship between insulin secretion rate (ISR) and plasma glucose, is not standardized and often involves any of a number of β-cell function indices. We compared β-cell function by using popular indices obtained during basal conditions and after glucose ingestion, including the HOMA-B index, the basal ISR (or plasma insulin)-to-plasma glucose concentration ratio, the insulinogenic and ISRogenic indices, the ISR (or plasma insulin)-to-plasma glucose concentration areas (or incremental areas) under the curve ratio, and the disposition index, which integrates a specific β-cell function index value with an estimate of insulin sensitivity, between lean people with normal fasting glucose (NFG) and normal glucose tolerance (NGT) (n = 50) and four groups of people with obesity (n = 188) with 1) NFG-NGT, 2) NFG and impaired glucose tolerance (IGT), 3) impaired fasting glucose (IFG) and IGT, and 4) type 2 diabetes. We also plotted the ISR-plasma glucose relationship before and after glucose ingestion and used a statistical mixed-effects model to evaluate group differences in this relationship (i.e., β-cell function). Index-based group differences in β-cell function produced contradicting results and did not reflect the group differences of the actual observed ISR-glucose relationship or, in the case of the disposition index, group differences in glycemic status. The discrepancy in results is likely due to incorrect mathematical assumptions that are involved in computing indices, which can be overcome by evaluating the relationship between ISR and plasma glucose with an appropriate statistical model. Data obtained with common β-cell function indices should be interpreted cautiously.

ARTICLE HIGHLIGHTS

Impaired plasma glucose clearance is a key determinant of fasting hyperglycemia in people with obesity

OBJECTIVE

The objective of this study was to evaluate the relative importance of the basal rate of glucose appearance (Ra) in the circulation and the basal rate of plasma glucose clearance in determining fasting plasma glucose concentration in people with obesity and different fasting glycemic statuses.

METHODS

The authors evaluated basal glucose kinetics in 33 lean people with normal fasting glucose (<100 mg/dL; Lean < 100 group) and 206 people with obesity and normal fasting glucose (Ob < 100 group, n = 118), impaired fasting glucose (100-125 mg/dL; Ob 100-125 group, n = 66), or fasting glucose diagnostic of diabetes (≥126 mg/dL; Ob ≥ 126 group, n = 22).

RESULTS

Although there was a large (up to three-fold) range in glucose Ra within each group, the ranges in glucose concentration in the Lean < 100, Ob < 100, and Ob 100-125 groups were small because of a close relationship between glucose Ra and clearance rate. However, the glucose clearance rate at any Ra value was lower in the hyperglycemic than the normoglycemic groups. In the Ob ≥ 126 group, plasma glucose concentration was primarily determined by glucose Ra, because glucose clearance was markedly attenuated.

CONCLUSIONS

Fasting hyperglycemia in people with obesity represents a disruption of the precisely regulated integration of glucose production and clearance rates.

Metabolic Abnormalities Following Tirzepatide Monotherapy in Japanese Patients with Type 2 Diabetes: A Phase 3 SURPASS J-mono Post Hoc Analysis

INTRODUCTION

The presence of metabolic abnormalities in patients with type 2 diabetes (T2D) increases the risk of cardiovascular disease and other comorbidities. This analysis compared the effects of tirzepatide (5, 10, and 15 mg) and dulaglutide 0.75 mg on the prevalence of metabolic abnormalities in Japanese patients with T2D.

METHODS

This was a post hoc analysis of SURPASS J-mono, a multicenter, randomized, double-blind, active-controlled, parallel-group, phase 3 trial that compared the efficacy and safety of tirzepatide monotherapy (5, 10, and 15 mg) to dulaglutide 0.75 mg in Japanese patients with T2D. Thresholds for abnormalities were based on the Japanese criteria for metabolic syndrome. Proportions of participants meeting a composite endpoint (visceral fat accumulation measured by waist circumference plus two or more of dyslipidemia, hypertension, or hyperglycemia) or individual component thresholds were calculated at baseline and week 52 for the overall population and for baseline body mass index (BMI) subgroups (< 25, 25 to < 30, and ≥ 30 kg/m2).

RESULTS

Of 636 randomized participants, 431 (67.8%) met the composite endpoint at baseline, with similar findings observed across treatment arms. At week 52, the proportion of participants on treatment that met the composite endpoint was 31.7%, 23.0%, and 14.2% in the tirzepatide 5-, 10-, and 15-mg arms, respectively, and 56.5% in the dulaglutide arm (p < 0.001). A higher proportion met the composite endpoint at baseline in the BMI 25 to < 30 and ≥ 30 kg/m2 subgroups (73.2-79.3%) compared with the < 25 kg/m2 subgroup (45.3%), with reductions observed across all BMI subgroups treated with tirzepatide. The proportion of participants with individual metabolic abnormalities showed similar trends to those observed for the composite endpoint. Tirzepatide was consistently superior to dulaglutide across all assessments.

CONCLUSIONS

Tirzepatide reduced the prevalence of multiple metabolic abnormalities, indicating tirzepatide may have metabolic benefit in Japanese patients with T2D.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT03861052.

Prevention of cardiorenal complications in people with type 2 diabetes and obesity

Traditional approaches to prevention of the complications of type 2 diabetes (T2D) and obesity have focused on reduction of blood glucose and body weight. The development of new classes of medications, together with evidence from dietary weight loss and bariatric surgery trials, provides new options for prevention of heart failure, chronic kidney disease, myocardial infarction, stroke, metabolic liver disease, cancer, T2D, and neurodegenerative disorders. Here I review evidence for use of lifestyle modification, SGLT-2 inhibitors, GLP-1 receptor agonists, selective mineralocorticoid receptor antagonists, and bariatric surgery, for prevention of cardiorenal and metabolic complications in people with T2D or obesity, highlighting the contributions of weight loss, as well as weight loss-independent mechanisms of action. Collectively, the evidence supports a tailored approach to selection of therapeutic interventions for T2D and obesity based on the likelihood of developing specific complications, rather than a stepwise approach focused exclusively on glycemic or weight control.

Single anastomosis duodeno-ileal bypass with sleeve gastrectomy generates sustained improvement of glycemic control compared with sleeve gastrectomy in the diet-induced obese rat model

Bariatric surgery has become a recognized and effective procedure for treating obesity and type 2 diabetes (T2D). Our objective was to directly compare the caloric intake-independent effects of sleeve gastrectomy (SG) and single anastomosis duodenoileal bypass with SG (SADI-S) on glucose tolerance in rats with diet-induced obesity (DIO) and to elucidate the differences between bariatric surgery and caloric restriction.A total of 120 adult male Wistar rats with DIO and insulin resistance were randomly assigned to surgical (sham operation, SG, and SADI-S) and dietary (pair-feeding the amount of food eaten by animals undergoing the SG or SADI-S surgeries) interventions. Body weight and food intake were weekly monitored, and 6 weeks after interventions, fasting plasma glucose, oral glucose and insulin tolerance tests, plasma insulin, adiponectin, GIP, GLP-1, and ghrelin levels were determined.The body weight of SADI-S rats was significantly (p < 0.001) lower as compared to the sham-operated, SG, and pair-fed groups. Furthermore, SADI-S rats exhibited decreased whole body fat mass (p < 0.001), lower food efficiency rates (p < 0.001), and increased insulin sensitivity, as well as improved glucose and lipid metabolism compared to that of the SG and pair-fed rats.SADI-S was more effective than SG, or caloric restriction, in improving glycemic control and metabolic profile, with a higher remission of insulin resistance as well as long-term weight loss.

2. Diagnosis and Classification of Diabetes: Standards of Care in Diabetes-2024

The American Diabetes Association (ADA) "Standards of Care in Diabetes" includes the ADA's current clinical practice recommendations and is intended to provide the components of diabetes care, general treatment goals and guidelines, and tools to evaluate quality of care. Members of the ADA Professional Practice Committee, an interprofessional expert committee, are responsible for updating the Standards of Care annually, or more frequently as warranted. For a detailed description of ADA standards, statements, and reports, as well as the evidence-grading system for ADA's clinical practice recommendations and a full list of Professional Practice Committee members, please refer to Introduction and Methodology. Readers who wish to comment on the Standards of Care are invited to do so at professional.diabetes.org/SOC.

1-year weight change after diabetes diagnosis and long-term incidence and sustainability of remission of type 2 diabetes in real-world settings in Hong Kong: An observational cohort study

BACKGROUND

Clinical trials have demonstrated that remission of type 2 diabetes can be achieved following sustained weight loss. However, the feasibility of achieving diabetes remission through weight management in real-world settings remains unclear. In this study, we aimed to examine the association of weight change at 1 year after diabetes diagnosis with long-term incidence and sustainability of type 2 diabetes remission in real-world settings in Hong Kong.

METHODS AND FINDINGS

This was a population-based observational cohort study. The territory-wide Risk Assessment and Management Programme for Diabetes Mellitus (RAMP-DM) provides regular comprehensive assessments of metabolic control and complication screening for people with diabetes in Hong Kong. We included 37,326 people with newly diagnosed type 2 diabetes who were enrolled in the RAMP-DM between 2000 and 2017, followed until 2019. Diabetes remission was defined as 2 consecutive HbA1c <6.5% measurements at least 6 months apart in the absence of glucose-lowering drugs (GLDs) and with no record of GLDs at least 3 months before these measurements. During a median follow-up of 7.9 years, 6.1% (2,279) of people achieved diabetes remission, with an incidence rate of 7.8 (95% CI: 7.5, 8.1) per 1,000 person-years. After adjusting for age at diabetes diagnosis, sex, assessment year, body mass index, other metabolic indices, smoking, alcohol drinking, and medication use, the hazard ratio (HR) for diabetes remission was 3.28 (95% CI: 2.75, 3.92; p < 0.001) for people with ≥10% weight loss within 1 year of diagnosis, 2.29 (95% CI: 2.03, 2.59; p < 0.001) for those with 5% to 9.9% weight loss, and 1.34 (95% CI: 1.22, 1.47; p < 0.001) for those with 0% to 4.9% weight loss compared to people with weight gain. During a median follow-up of 3.1 years, 67.2% (1,531) of people who had achieved diabetes remission returned to hyperglycaemia, with an incidence rate of 184.8 (95% CI: 175.5, 194.0) per 1,000 person-years. The adjusted HR for returning to hyperglycaemia was 0.52 (95% CI: 0.41, 0.65; p < 0.001) for people with ≥10% weight loss, 0.78 (95% CI: 0.68, 0.92; p = 0.002) for those with 5% to 9.9% weight loss, and 0.90 (95% CI: 0.80, 1.01; p = 0.073) for those with 0% to 4.9% weight loss compared to people with weight gain. Diabetes remission was associated with a 31% (HR: 0.69, 95% CI: 0.52, 0.93; p = 0.014) decreased risk of all-cause mortality. The main limitation of the study is that the reliability of HbA1c used to define diabetes remission can be affected by other medical conditions. Furthermore, we did not have data on bariatric surgery.

CONCLUSIONS

In this study, greater weight loss within the first year of diabetes diagnosis was associated with an increased likelihood of achieving diabetes remission and a decreased risk of returning to hyperglycaemia among those who had achieved diabetes remission. However, both the incidence of diabetes remission and the probability of its long-term sustainability were low with conventional management in real-world settings, in an era when the importance of weight loss was not fully appreciated. Our study provides evidence for policymakers to design and implement early weight management interventions and diabetes remission initiatives.

Glucagon-Like Peptide 1 Analogues as Adjunctive Therapy for Patients With Type 1 Diabetes: An Updated Systematic Review and Meta-analysis

CONTEXT

Concomitant obesity is common among patients with type 1 diabetes mellitus (T1DM), yet adjunctive therapy options are scarce.

OBJECTIVE

We assess the efficacy and adverse outcomes of glucagon-like peptide 1 (GLP-1) analogues when used as adjunctive therapy for T1DM.

METHOD

PubMed, EMBASE, Cochrane Central, and Scopus databases were searched for randomized controlled trials up to December 2022. Efficacy outcomes were A1c level, body weight, and total daily insulin (TDI) after ≥12 weeks of GLP-1 therapy. We also assessed 12 different adverse outcomes. Subgroup analysis was done for newly diagnosed or C-peptide positive (C-pos) patients. We report the certainty of evidence based on the GRADE assessment tool.

RESULTS

A total of 24 studies using 4 different GLP-1 analogues with a total of 3377 patients were included. Liraglutide had the most substantial evidence with effect sizes on A1c (-0.09%/mg), weight (-2.2 kg/mg), and TDI (-4.32 IU/mg). Liraglutide dose was the greatest predictor of greater average weight loss and TDI decrease but was associated with higher odds of nausea (OR 6.5; 95% CI, 5.0-8.4) and ketosis (OR 1.8; 95% CI, 1.1-2.8). Odds of severe (OR 0.67; 95% CI, 0.43-1.04) or symptomatic hypoglycemia (OR 0.89; 95% CI, 0.53-1.51) were not significantly elevated. Among C-pos patients, greater A1c decrease (-0.51% vs -0.28%) but similar weight loss and TDI were seen. Effect sizes for exenatide were similar, but studies had higher risk of bias and safety data were sparse.

CONCLUSION

Our meta-analysis supports therapeutic benefits of liraglutide for patients with T1DM mainly for weight loss and insulin dose reduction. Newly diagnosed or C-pos patients do not appear to experience greater weight loss benefits.

Bariatric Surgery for Adults With Class I Obesity and Difficult-to-Manage Type 2 Diabetes: A Health Technology Assessment

Background

Many individuals with type 2 diabetes are classified as either overweight or obese. A patient may be described as having difficult-to-manage type 2 diabetes if their HbA1c levels remain above recommended target levels, despite efforts to treat it with lifestyle changes and pharmacotherapy. Bariatric surgery refers to procedures that modify the gastrointestinal tract. In patients with class II or III obesity, bariatric surgery has resulted in substantial weight loss, improved quality of life, reduced mortality risk, and resolution of type 2 diabetes. There is some evidence suggesting these outcomes may also be possible for patients with class I obesity as well. We conducted a health technology assessment of bariatric surgery for adults with class I obesity and difficult-to-manage type 2 diabetes, which included an evaluation of effectiveness, safety, cost-effectiveness, the budget impact of publicly funding bariatric surgery, and patient preferences and values.

Methods

We performed a systematic clinical literature review. We assessed the risk of bias of each included study, using the Cochrane Risk of Bias tool for randomized controlled trials, the Risk of Bias in Non-randomized Studies - of Interventions (ROBINS-I) tool for cohort studies, and the Risk of Bias in Systematic Reviews (ROBIS) tool for systematic reviews; we assessed the quality of the body of evidence according to the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) Working Group criteria. We performed a systematic economic literature review and conducted a cost-utility analysis of bariatric surgery in comparison with nonsurgical usual care over a lifetime horizon from a public payer perspective. We also analyzed the budget impact of publicly funding bariatric surgery for adults with class I obesity and difficult-to-manage type 2 diabetes in Ontario. To contextualize the potential value of bariatric surgery, we spoke with people with obesity and type 2 diabetes who had undergone or were considering this procedure.

Results

We included 14 studies in the clinical evidence review. There were large increases in diabetes remission rates (GRADE: Low to Very low) and large reductions in body mass index (GRADE: Low to Very low) with bariatric surgery than with medical management. Bariatric surgery may also reduce the use of medications for type 2 diabetes (GRADE: Low) and may improve quality of life for people with class I obesity and difficult-to-manage type 2 diabetes compared with medical management. (GRADE: Low)Our economic evidence review included 5 cost-effectiveness studies; none were conducted in a Canadian setting, and 4 were considered partially applicable to our research question. Most studies found bariatric surgery to be cost-effective compared to standard care for patients with class I obesity and type 2 diabetes; however, the applicability of these results to the Ontario context is uncertain due to potential differences in clinical practice, resource utilization, and unit costs.Our primary economic evaluation found that over a lifetime horizon, bariatric surgery was more costly (incremental cost: $8,151 per person) but also more effective than current usual care (led to a 0.339 quality-adjusted life-year [QALY] gain per person). The cost increase was driven by costs associated with surgery (before, after, and during surgery), and the QALY gain was due to life-years gained. Results were sensitive to the bariatric surgery cost and assumptions regarding its long-term benefits with respect to weight loss and diabetes remission.Publicly funding 50 bariatric surgeries in year 1, and gradually increasing to 250 surgeries in year 5, for people with class I obesity and difficult-to-manage type 2 diabetes would lead to budget increases of $0.55 million in year 1 to $2.45 million in year 5, for a total of $7.63 million over 5 years.The people with obesity and type 2 diabetes with whom we spoke reported that bariatric surgery was generally seen as a positive treatment option, and those who had undergone the procedure reported positively on its value as a treatment to manage their weight and diabetes.

Conclusions

For adults with class I obesity and difficult-to-manage type 2 diabetes, bariatric surgery may be more clinically effective and cost-effective than medical management. Compared with medical management in people with class I obesity and difficult-to-manage type 2 diabetes, bariatric surgery may result in large increases in diabetes remission rates, large reductions in BMI, and reduced medication use for type 2 diabetes, improved quality of life. Over a lifetime horizon, bariatric surgery led to a cost increase and QALY gain. Bariatric surgery can result in postsurgical complications that are not faced by those receiving medical management. The cost-effectiveness of bariatric surgery depends on its long-term impacts on obesity-related and diabetes-related complications, which could be uncertain.Our budget impact analysis suggests that publicly funding bariatric surgery in Ontario for people with class I obesity and difficult-to-manage type 2 diabetes would lead to a budget increase of $7.63 million over 5 years.For people with obesity and type 2 diabetes, bariatric surgery was seen as a potential positive treatment option to manage their weight and diabetes.

Differential effect of gastric bypass versus sleeve gastrectomy on insulinotropic action of endogenous incretins

OBJECTIVE

Prandial hyperinsulinemia after Roux-en-Y gastric bypass surgery (GB), and to lesser degree after sleeve gastrectomy (SG), has been attributed to rapid glucose flux from the gut and increased insulinotropic gut hormones. However, β-cell sensitivity to exogenous incretin is reduced after GB. This study examines the effect of GB versus SG on prandial glycemia and β-cell response to increasing concentrations of endogenous incretins.

METHODS

Glucose kinetics, insulin secretion rate (ISR), and incretin responses to 50-g oral glucose ingestion were compared between ten nondiabetic participants with GB versus nine matched individuals with SG and seven nonoperated normal glucose tolerant control individuals (CN) with and without administration of 200 mg of sitagliptin.

RESULTS

Fasting glucose and hormonal levels were similar among three groups. Increasing plasma concentrations of endogenous incretins by two- to three-fold diminished prandial glycemia and increased β-cell secretion in all three groups (p < 0.05), but insulin secretion per insulin sensitivity (i.e., disposition index) was increased only in GB (p < 0.05 for interaction). However, plot of the slope of ISR (from premeal to peak values) versus plasma glucagon-like peptide-1 concentration was smaller after GB compared with SG and CN.

CONCLUSIONS

After GB, increasing incretin activity augments prandial β-cell response whereas the β-cell sensitivity to increasing plasma concentrations of endogenous incretin is diminished.

Effect of Bariatric Surgery on Metabolic Syndrome in Chinese Patients with Low Body Mass Index: a Propensity Score Matching Study

BACKGROUND

Bariatric surgery (BS) is known to improve the components of metabolic syndrome (MS) in patients with obesity. However, few studies have evaluated the effect of BS on patients with MS at low BMI levels. The study aims to assess the effect of BS on MS in patients with low BMI by comparing BS with medical therapy (MT).

METHODS

A total of 271 patients with MS who underwent BS and MT at a single institution were reviewed in this retrospective cohort study. A 1:1 propensity score matching was performed for the BS and MT groups with BMI<35 kg/m2. We analyzed the 5 years effect of BS versus MT on the remission of MS, its components, atherosclerotic cardiovascular disease (ASCVD) risk, and medication used.

RESULTS

Patients in the MT group showed a decrease in the prevalence of MS to 62% at the 1st year and 10% at the 5th year. In the BS group, MS prevalence in patients with BMI<35 kg/m2 decreased to 30% and 9% at the 1st and 5th year, whereas in patients with BMI≥35 kg/m2 was 26% and 7%, respectively. The 10-year ASCVD risk and the lifetime ASCVD were significantly decreased 5 years after BS in patients with BMI<35 kg/m2. The number and daily drug dose of hypoglycemic drugs, antihypertensive medications, and lipid-lowering drugs were reduced from baseline in both BS and MT groups.

CONCLUSION

Bariatric surgery significantly improves MS remission rates and long-term cardiovascular risk in Chinese patients with metabolic syndrome and a BMI <35 kg/m2.

Bariatric Surgery Alters the Postprandial Recovery From Hypoglycemia, Mediated by Cholinergic Signal

Roux-en-Y gastric bypass (GB) and sleeve gastrectomy (SG) surgeries increase prandial insulin and glucagon secretion but reduce the endogenous glucose production (EGP) response to hypoglycemia in comparison with control subjects who had not undergone gastric surgery (CN), suggesting that parasympathetic nervous system (PNS) plays a role. Here, we investigated the effect of acute PNS blockade on the post-meal counterregulatory response to insulin-induced hypoglycemia in GB and SG compared with CN. Glucose kinetics and islet cell secretion were measured in nine subjects without diabetes with GB and seven with SG and five CN during hyperinsulinemic-hypoglycemic clamp (∼3.2 mmol/L) combined with meal ingestion on two separate days with and without intravenous atropine infusion. Glucose and hormonal levels were similar at baseline and during steady-state hypoglycemia before meal ingestion in three groups and unaffected by atropine. Atropine infusion diminished prandial systemic appearance of ingested glucose (RaO) by 30%, EGP by 40%, and glucagon response to hypoglycemia by 90% in CN. In GB or SG, blocking PNS had no effect on the RaO or meal-induced hyperglucagonemia but increased EGP in SG without any effect in GB (P < 0.05 interaction). These findings indicate that cholinergic signal contributes to the recovery from hypoglycemia by meal consumption in humans. However, bariatric surgery dissipates PNS-mediated physiologic responses to hypoglycemia in the fed state.

ARTICLE HIGHLIGHTS

Rerouted gut after Roux-en-Y gastric bypass (GB) and, to a lesser degree, after sleeve gastrectomy (SG) leads to larger glucose excursion and lower nadir glucose, predisposing individuals to hypoglycemia. Despite prandial hyperglucagonemia, endogenous glucose production response to hypoglycemia is reduced after GB or SG. Parasympathetic nervous system (PNS) activity plays a key role in regulation of glucose kinetics and islet cell function. We examined the effect of acute PNS blockade on counterregulatory glucose and islet cell response to meal ingestion during insulin-induced hypoglycemia among GB, SG, and control subjects who had not had gastric surgery. Our findings demonstrate that cholinergic signal is critical in the recovery from hypoglycemia by meal ingestion in humans who have not had gastric surgery, although prandial PNS-mediated physiologic responses to hypoglycemia are differentially changed by GB and SG.

Beta-cell function in type 2 diabetes (T2DM): Can it be preserved or enhanced?

Type 2 diabetes (T2DM) is a complex metabolic disorder manifested by hyperglycemia, insulin resistance, and deteriorating beta-cell function. A way to prevent progression of the disease might be to enhance beta-cell function and insulin secretion. However, most previous studies examined beta-cell function while patients were using glycemia-lowering agents without an adequate period off medications (washout). In the present review we focus on studies with a washout period. We performed a literature search (2010 to June 2021) using beta-cell function and enhancement. The evidence shows that beta-cell function can be enhanced. Bariatric surgery and very low calorie diets show improvement in beta-cell function in many individuals. In addition, use of glucagon-like peptide-1 receptor agonists for prolonged periods (3 years or more) can also lead to improvement of beta-cell function. Further research is needed to understand the mechanisms leading to improved beta-cell function and identify agents that could enhance beta-cell function in patients with T2DM.

Cellular mechanism of diabetes remission by bariatric surgery

Bariatric surgery is a powerful therapy for type 2 diabetes in patients with obesity. The mechanism of insulin sensitization by surgery has been extensively investigated in weight loss-dependent and weight loss-independent conditions. However, a consensus remains to be established regarding the underlying mechanisms. Energy deficit induced by calorie restriction (CR), that occurs both before and after surgery, represents a unique physiological basis for insulin sensitization regardless of weight loss. In support, we integrate evidence in the literature to provide an energy-based view of insulin sensitization as follows: surgery improves insulin sensitivity through the energy deficit induced by CR, leading to correction of mitochondrial overload in multiple cell types; this then triggers functional reprogramming of relevant tissues leading to diabetes remission.

Roux-en-Y and One-Anastomosis Gastric Bypass Surgery Are Superior to Sleeve Gastrectomy in Lowering Glucose and Cholesterol Levels Independent of Weight Loss: a Propensity-Score Weighting Analysis

BACKGROUND

The superior effects of gastric bypass surgery in preventing cardiovascular diseases compared with sleeve gastrectomy are well-established. However, whether these effects are independent of weight loss is not known.

METHODS

In this retrospective cohort study, we compared the change in cardiometabolic risks of 1073 diabetic patients undergoing Roux-en-Y gastric bypass (RYGB) (n = 265), one-anastomosis gastric bypass (OAGB) (n = 619), and sleeve gastrectomy (SG) (n = 189) with equivalent weight loss from the Min-Shen General Hospital. Propensity score-weighting, multivariate regression, and matching were performed to adjust for baseline differences.

RESULTS

After 12 months, OAGB and, to a lesser extent, RYGB exhibited superior effects on glycemic control compared with SG in patients with equivalent weight loss. The effect was significant in patients with mild-to-modest BMI reduction but diminished in patients with severe BMI reduction. RYGB and OAGB had significantly greater effects in lowering total and low-density lipoprotein cholesterol than SG, regardless of weight loss. The results of matching patients with equivalent weight loss yielded similar results. The longer length of bypassed biliopancreatic (BP) limbs was correlated with a greater decrease in glycemic levels, insulin resistance index, lipids, C-reactive protein (CRP) levels, and creatinine levels in patients receiving RYBG. It was correlated with greater decreases in BMI, fasting insulin, insulin resistance index, and C-reactive protein levels in patients receiving OAGB.

CONCLUSION

Diabetic patients receiving OAGB and RYGB had lower glucose and cholesterol levels compared with SG independent of weight loss. Our results suggest diabetic patients with cardiovascular risk factors such as hypercholesterolemia to receive bypass surgery.

Identification of myokines susceptible to improve glucose homeostasis after bariatric surgery

IMPORTANCE AND OBJECTIVE

The identification of myokines susceptible to improve glucose homeostasis following bariatric surgery could lead to new therapeutic approaches for type 2 diabetes.

METHODS

Changes in the homeostasis model assessment (HOMA) test were assessed in patients before and 3 months after bariatric surgery. Changes in myokines expression and circulating levels were assessed using real-time quantitative polymerase chain reaction (RT-qPCR) and enzyme-linked immunosorbent assay (ELISA). Myokines known to regulate glucose homeostasis were identified using literature (targeted study) and putative myokines using RNA-sequencing (untargeted study). A linear regression analysis adjusted for age and sex was used to search for associations between changes in the HOMA test and changes in myokines.

RESULTS

In the targeted study, brain-derived neurotrophic factor (BDNF) expression was upregulated (+30%, P = .006) while BDNF circulating levels were decreased (-12%, P = .001). Upregulated BDNF expression was associated with decreased HOMA of insulin resistance (HOMA-IR) (adjusted estimate [95% confidence interval {CI}]: -0.51 [-0.88 to -0.13], P = .010). Decreased BDNF serum levels were associated with decreased HOMA of beta-cell function (HOMA-B) (adjusted estimate [95% CI] = 0.002 [0.00002-0.0031], P = .046). In the untargeted study, upregulated putative myokines included XYLT1 (+64%, P < .001), LGR5 (+57, P< .001), and SPINK5 (+46%, P < .001). Upregulated LGR5 was associated with decreased HOMA-IR (adjusted estimate [95% CI] = -0.50 [-0.86 to -0.13], P = .009). Upregulated XYLT1 and SPINK5 were associated with increased HOMA of insulin sensitivity (HOMA-S) (respectively, adjusted estimate [95% CI] = 109.1 [28.5-189.8], P = .009 and 16.5 [0.87-32.19], P = .039).

CONCLUSIONS

Improved glucose homeostasis following bariatric surgery is associated with changes in myokines expression and circulating levels. In particular, upregulation of BDNF, XYLT1, SPINK5, and LGR5 is associated with improved insulin sensitivity. These results suggest that these myokines could contribute to improved glucose homeostasis following bariatric surgery.

STUDY REGISTRATION

NCT03341793 on ClinicalTrials.gov (https://clinicaltrials.gov/).

Differential effects of bariatric surgery and caloric restriction on hepatic one-carbon and fatty acid metabolism

Weight loss interventions, including dietary changes, pharmacotherapy, or bariatric surgery, prevent many of the adverse consequences of obesity, and may also confer intervention-specific benefits beyond those seen with decreased weight alone. We compared the molecular effects of different interventions on liver metabolism to understand the mechanisms underlying these benefits. Male rats on a high-fat, high-sucrose diet underwent sleeve gastrectomy (SG) or intermittent fasting with caloric restriction (IF-CR), achieving equivalent weight loss. The interventions were compared to ad-libitum (AL)-fed controls. Analysis of liver and blood metabolome and transcriptome revealed distinct and sometimes contrasting metabolic effects between the two interventions. SG primarily influenced one-carbon metabolic pathways, whereas IF-CR increased de novo lipogenesis and glycogen storage. These findings suggest that the unique metabolic pathways affected by SG and IF-CR contribute to their distinct clinical benefits, with bariatric surgery potentially influencing long-lasting changes through its effect on one-carbon metabolism.